On 11/30/20 8:59 AM, Anshuman Khandual wrote: > This series adds a mechanism allowing platforms to weigh in and prevalidate > incoming address range before proceeding further with the memory hotplug. > This helps prevent potential platform errors for the given address range, > down the hotplug call chain, which inevitably fails the hotplug itself. > > This mechanism was suggested by David Hildenbrand during another discussion > with respect to a memory hotplug fix on arm64 platform. > > https://lore.kernel.org/linux-arm-kernel/1600332402-30123-1-git-send-email-anshuman.khandual@xxxxxxx/ > > This mechanism focuses on the addressibility aspect and not [sub] section > alignment aspect. Hence check_hotplug_memory_range() and check_pfn_span() > have been left unchanged. Wondering if all these can still be unified in > an expanded memhp_range_allowed() check, that can be called from multiple > memory hot add and remove paths. > > This series applies on v5.10-rc6 and has been slightly tested on arm64. > But looking for some early feedback here. > > Changes in RFC V2: > > Incorporated all review feedbacks from David. > > - Added additional range check in __segment_load() on s390 which was lost > - Changed is_private init in pagemap_range() > - Moved the framework into mm/memory_hotplug.c > - Made arch_get_addressable_range() a __weak function > - Renamed arch_get_addressable_range() as arch_get_mappable_range() > - Callback arch_get_mappable_range() only handles range requiring linear mapping > - Merged multiple memhp_range_allowed() checks in register_memory_resource() > - Replaced WARN() with pr_warn() in memhp_range_allowed() > - Replaced error return code ERANGE with E2BIG There is one build failure with MEMORY_HOTPLUG=y and MEMORY_HOTREMOVE=n. There are warnings on arm64 and s390 platforms when built with W=1 due to lack of prototypes required with -Wmissing-prototypes. I have fixed all these problems for the next iteration when there is broad agreement on the overall approach.
